Asymmetric catalysis is a good way to obtain chiral drugs of single enantiomer. It is capable of generating large amount of chiral compounds using small amount of catalysts, eliminating or even avoiding the production of ineffective compounds, which is not only environmentally beneficial, but also capable of achieving good atomic economy and avoiding complicated racemic resolution.
The design and synthesis of highly selective and catalytic chiral catalysts is of vital importance for the asymmetric catalysis. In an asymmetric reaction catalyzed by a transition metal, the chiral ligand coordinating with the metal is essential for the reactivity and enantioselectivity.
Since appearance of axial chiral ligand BINAP, the ligands having biphenyl or binaphthyl backbone have drawn much attention. Mainly due to the fact that the biphenyl or binaphthyl backbone with structural flexibility could spin freely along the axis, the catalytic systems derived from it have achieved rather good results in this art.
On the other hand, most asymmetric catalytic reaction systems have only one catalytic center which is activated through coordinating with the substrate and reagents, forming a thermodynamically stable transition state under the influence of chiral environment of the ligand, and achieving asymmetric induction eventually. Recently, much attention has been drawn to bimetallic ligands. The bimetallic ligand, as a new backbone of organometallics, may function through the coordination of two metals so as to afford excellent chemical selectivity and enantioselectivity for many reactions. Therefore, the development of bimetallic ligands having axial chirality has become a major research focus in both academic and industrial field.
Through a literature research in the prior art, no subject matter the same as or similar to that of the present invention is found up to now.